Linq：按名称选择所有项目，计数等于0

Question

I have table orders(name, date, price)

  horse, 7.5.2012, 100
  cat, 14.5.2012, 50
  horse, 8.5.2012, 70,
  dog, 13.5.2012, 40

and I want to show up orders name and sum of price on Monday. Output what I want:

  horse, 100
  cat, 50
  dog, 0

but now I have only this:

  horse, 100
  cat, 50

with this linq query

  from c in orders
  where (int)c.date.DayOfWeek == this._monday
  group c by c.name into g
  select new {
    Name = g.Key,
    Price = g.Sum(c => c.Price)
  }

Can you help me, what I must change to get output what I want, please? :)

Answer 1

Try groupping first then do the filtering for Monday

from c in orders  
group c by c.name into g
  select new {
    Name = g.Key,
    Price = g.Where(c => (int)c.date.DayOfWeek == this._monday).Sum(c => c.Price)
  }